The 1916 United States Senate election in Indiana took place on November 7, 1916. Incumbent Democratic U.S. senator and Senate Majority Leader John W. Kern ran for re-election to a second term in office. He was defeated by Republican Harry New, a former chairman of the Republican National Committee.
After losing the primary, Watson ran in the special election for Indiana's other Senate seat caused by the death of Senator Benjamin F. Shively, which he won over Indiana's other Senator Thomas Taggart. Watson would be sworn in as a U.S. senator 3 months before Senator-elect New's term began.
Kern died five months after leaving the U.S. Senate.